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F Panzera

Publications and source records attributed to F Panzera.

At least 19 recordsLinked to original sources
PubMed2006

Chromosomal variation and genome size support existence of cryptic species of Triatoma dimidiata with different epidemiological importance as Chagas disease vectors.

The wide geographical distribution of Triatoma dimidiata, one of the three major vectors of Chagas disease, ranges from Mexico to northern Peru. Since this species occupies a great diversity of artificial and natural ecotopes, its eradication is extremely difficult. In order to assist control efforts, we used chromosome analyses and DNA amount as taxonomic markers to study genetic variability in populations of T. dimidiata from Mexico, Guatemala, El Salvador and Colombia. We differentiated three groups or cytotypes defined by characteristic chromosome C-banding patterns and genome size measured by flow cytometry. The three cytotypes are restricted to different geographic locations. Cytotype 1 occurs in Mexico (excluding Yucatán), Guatemala (excluding Petén), El Salvador and Colombia. Cytotype 2 occurs in Yucatán and cytotype 3 occurs in Petén. Cytotype 1, commonly associated with domestic and peridomestic environments but also inhabiting sylvatic ecotopes, is the most widespread and with major epidemiological significance. In contrast, the Yucatán cytotype inhabits wild ecotopes but increasingly enters houses, while the Petén cytotype appears exclusively sylvatic. We suggest that these cytotypes represent cryptic species of T. dimidiata with different epidemiological relevance as Chagas disease vectors. Poor ability to colonize human dwellings, together with their restricted geographic distribution, indicate that the Yucatán and Petén putative species probably have much less epidemiological significance than cytotype 1. Thus, the genetic markers we describe are powerful tools to differentiate cryptic species in T. dimidiata with different epidemiological significance, contributing to planning the most effective control measures.

Animals↗
PubMed2005

Origin and phylogeography of the Chagas disease main vector Triatoma infestans based on nuclear rDNA sequences and genome size.

For about half of all Chagas disease cases T. infestans has been the responsible vector. Contributing to its genetic knowledge will increase our understanding of the capacity of geographic expansion and domiciliation of triatomines. Populations of all infestans subcomplex species, T. infestans, T. delpontei, T. platensis and T. melanosoma and the so-called T. infestans "dark morph", from many South American countries were studied. A total of 10 and 7 different ITS-2 and ITS-1 haplotypes, respectively, were found. The total intraspecific ITS-2 nucleotide variability detected in T. infestans is the highest hitherto known in triatomines. ITS-1 minisatellites, detected for the first time in triatomines, proved to be homologous and thus become useful markers. Calculations show that ITS-1 evolves 1.12-2.60 times faster than ITS-2. Despite all species analyzed presenting the same n=22 chromosome number, a large variation of the haploid DNA content was found, including a strikingly high DNA content difference between Andean and non-Andean specimens of T. infestans (mean reduction of 30%, with a maximum of up to 40%) and a correlation between presence/absence of minisatellites and larger/smaller genome size. Population genetics analysis of the eight composite haplotypes of T. infestans and net differences corroborate that there are clear differences between western and eastern populations (60%), and little genetic variation among populations (1.3%) and within populations (40%) within these two groups with migration rates larger than one individual per generation corresponding only to pairs of populations one from each of these groups. These values are indicative either of a large enough gene flow to prevent population differentiation by drift within each geographic area or a very recent spread, the latter hypothesis fitting available data better. Phylogenetic trees support a common ancestor for T. infestans and T. platensis, an origin of T. infestans in Bolivian highlands and two different dispersal lines, one throughout Andean regions of Bolivia and Peru and another in non-Andean lowlands of Chile, Paraguay, Argentina, Uruguay and Brazil.

Animals↗
PubMed2002

Nuclear rDNA ITS-2 sequences reveal polyphyly of Panstrongylus species (Hemiptera: Reduviidae: Triatominae), vectors of Trypanosoma cruzi.

Panstrongylus species are widely distributed throughout the Americas, where they act as vectors of Trypanosoma cruzi, agent of Chagas disease. Their intraspecific relationships, taxonomic position and phylogeny in relation to other Triatomini were explored using ribosomal DNA (rDNA) internal transcribed spacer 2 (ITS-2) sequence polymorphisms and maximum parsimony, distance and maximum likelihood analyses of 10 populations representing six species of the genus (P. megistus, P. geniculatus, P. rufotuberculatus, P. lignarius, P. herreri and P. chinai). At the subspecific level, P. megistus appeared more homogeneous than P. rufotuberculatus and P. geniculatus (both with broader distribution). Several dinucleotide microsatellites were detected in the sequences of given species. Many of these microsatellites (GC, TA, GT and AT) showed different number of repeats in different populations and thus, may be very useful for population differentiation and dynamics analyses in future studies. The sequences of P. lignarius (considered sylvatic) and P. herreri (a major disease vector in Peru) were identical, suggesting that these species should be synonymised. Intrageneric analysis showed a clear separation of P. rufotuberculatus, with closest relationships between P. geniculatus and P. chinai, and P. megistus occupying a separate branch. Genetic distances between Panstrongylus species (0.11585-0.22131) were higher than those between Panstrongylus and other Triatomini (16 species from central and North America and South America) (0.08617-0.11039). The distance between P. megistus and P. lignarius/herreri (0.22131) was the largest so far recorded in the tribe. The pronounced differences in length and nucleotide composition suggest a relatively old divergence of Panstrongylus species. P. rufotuberculatus was closer to Mesoamerican Triatoma, Meccus and Dipetalogaster species than to other Panstrongylus. All Panstrongylus clustered with the Mesoamerican clade; P. rufotuberculatus clustered with the phyllosoma complex and T. dimidiata, with D. maxima and T. barberi in a basal position. The rest of Panstrongylus appeared paraphyletically in the tree. This is evidence suggesting polyphyly within the genus Panstrongylus, whose species may be related to the ancestors giving rise to central and North American Triatomini.

Animals↗
PubMed2000

Meiosis in holocentric chromosomes: orientation and segregation of an autosome and sex chromosomes in Triatoma infestans (Heteroptera).

The meiotic behaviour of the X chromosome and one autosomal pair of the heteropteran Triatoma infestans was analysed by means of C-banding plus DAPI staining. At first metaphase, the X univalent is oriented with its long axis parallel to the equatorial plate, which suggests a holocentric interaction with the spindle fibres. After this initial orientation, kinetic activity is restricted to one of both chromatid ends. The election of the active chromatid end is random and it is independent of the end selected in the sister chromatid. At second metaphase, the X and Y chromatids associate side by side forming a pseudobivalent. After that, the kinetic activity is again restricted to either of both chromosomal ends in a random fashion. At first metaphase, the fourth autosomal bivalent shows two alternative random orientations depending on the chromosome end showing kinetic activity (DAPI positive or opposite). At second metaphase, half bivalents are oriented with their long axis parallel to the equatorial plate. Three different segregation patterns are observed. The kinetic activity can be localised: (i) in the end with the DAPI signal (46.9%), (ii) in the opposite end (44.6%) or (iii) in one DAPI-positive end in one chromatid and in the opposite end in the other one (8.5%). The existence of the last pattern indicates that the same end can show kinetic activity during both meiotic divisions. Our results provide new information on the comparative meiotic behaviour of autosomes and sex chromosomes in holocentric systems.

Animals↗
PubMed2000

Sylvatic population of Triatoma infestans from the Bolivian Chaco: from field collection to characterization.

A sylvatic Triatoma infestans DM (dark morph) population detected in the Bolivian Chaco was characterized and compared with various domestic ones. The degree of differentiation of DM was clearly within the T. infestans intra-specific level. Nevertheless marked chromatic and morphometric differences as well as differences in antennal pattern, chromosome banding and randomly amplified polymorphic DNA support the hypothesis of a distinct population. Continuous exchange of insects between wild and domestic habitats seems unlikely in the Chaco.

Animals↗
PubMed2000

Chromosome homogeneity in populations of Triatoma brasiliensis Neiva 1911 (Hemiptera - reduviidae - triatominae).

Triatoma brasiliensis is the most important vector of Chagas disease in the semiarid zone of the Northeast of Brazil. Several authors have reported the occurrence of four chromatic patterns with morphological, ecological, and genetic differences. In order to determine the existence of cytogenetic differentiation between these chromatic forms, we analyzed their karyotypes and the chromosome behavior during the male meiotic process. Triatoma brasiliensis shows distinct and specific chromosome characteristics, which differ from those observed in all other triatomine species. However, no cytogenetic differences were observed between the four chromatic forms of T. brasiliensis. The lack of chromosome differentiation among them could indicate that the populations of this species are in a process of differentiation that does not involve their chromosomal organization.

Animals↗
PubMed2000

[Laparoscopic appendectomy. Retrospective analysis of our experience compared with the literature].

BACKGROUND: The benefits of laparoscopic appendectomy (LA) remain controversial. This study reports a critical examination of our experience in a peripheral hospital. METHODS: A total of 128 appendectomies have been performed since January 1996, of which 63 (49%) were laparoscopic. The patients included 52 (82.5%) females and 11 (17.5%) males with a mean age of 20.8 years (range 11-46). Emergency surgery was required in 6 cases (9.5%) and was elective in 57 (90.5%). Appendectomy was performed during another operation in 3 cases (laparoscopic cholecystectomy). RESULTS: Mortality was nil. Morbidity was 1.7% (1 case). The index of conversion was 0%. Only one major complication occurred. This took the form of perforation of an ileal loop following accidental lesion during adhesiolysis. The intraoperative diagnosis was not confirmed in 12 (19%) cases: 9 ovarian cysts, 1 terminal ilieitis and 2 cases of acute salpingitis. In 10 cases (15%) surgery was associated with adhesiolysis, and in 6 cases (9.3%) the appendix was retrocecal. Mean operating time was 42 min (range 18-105 min). The mean hospitalisation was 3.3 days. CONCLUSIONS: The authors emphasise the numerous advantages of laparoscopic techniques in their experience, including excellent cosmetic results, reduced PO pain, rapid functional recovery, lower incidence of adhesion, wound infection and laparocele, and more cost-effective when mechanical staplers are not used. Owing to the ability to explore the entire abdominal cavity, the main advantage of this technique consisted in a correct differential diagnostic balance, especially in young women of child-bearing age, between appendectomy and pathologies of the uterus and adnexa.

Adolescent↗
PubMed1999

Mitochondrial DNA variation of Triatoma infestans populations and its implication on the specific status of T. melanosoma.

DNA sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome B gene was used to infer the genetic structure of nine geographical Triatoma infestans populations and their phylogenetic relationship with T. melanosoma and T. brasiliensis. T. infestans and T. melanosoma were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. No differences were found to distinguish the two species and the crosses between them yielded progeny. T. infestans populations presented four haplotypes that could be separated in two clusters: one formed by the samples from Bolivia (Andes and Chaco) and the other formed by samples from Argentina and Brazil. Silvatic and domestic T. infestans populations from Bolivia (Andes) were genetically identical.

Animals↗
PubMed1998

Alary polymorphism in Triatoma spinolai and its possible relationship with demographic strategy.

Among collections of Triatoma spinolai from various sites in northern Chile, adults from coastal populations are invariably wingless, whereas inland populations show balanced alary polymorphism between wingless females and males that are either winged or wingless. Laboratory crosses showed that male offspring from normal-winged parents were always winged (88% long-winged) and those from long-winged male parents were all long-winged. The male offspring from wingless males always included winged males: 11/33 = 33%, of which 8/11 = 73% were long-winged. An X-linked mutation is proposed to inhibit wing development. Field studies of population demography indicate that male alary polymorphism is advantageous in the desert environment of northern Chile.

Animals↗
PubMed1997

Meiotic behaviour of holocentric chromosomes: orientation and segregation of autosomes in Triatoma infestans (Heteroptera).

The meiotic behaviour of the holocentric chromosomes of the heteropteran species Triatoma infestans has been analysed by means of orcein staining and C-banding on squashed spermatocytes. We have focused our analysis on chromosome 3, which shows a large distal heterochromatic band at one of the ends of both homologues. At metaphase I, and independently of the chiasma position, two alternative orientations have been observed: either the heterochromatic or the euchromatic ends of both homologues are directed to opposite poles. At anaphase I, the kinetic activity is restricted to the same chromosome end (euchromatic or heterochromatic) of each homologue. The frequencies of these two alternatives are not random and differ significantly among the five individuals analysed. However, the euchromatic ends present kinetic activity at a higher frequency than the heterochromatic ends. At metaphase II, half-bivalents also show the kinetic activity restricted to either of the chromosome ends (euchromatic or heterochromatic). The frequencies of each alternative are inverted in anaphase II compared with those scored in anaphase I. Accordingly, those ends that present kinetic activity at anaphase I segregate reductionally during the first meiotic division and equationally during the second meiotic division. These results provide sound evidence on the meiotic behaviour of holocentric chromosomes, as regards the absence of chiasma terminalization and the modes of orientation and segregation.

Anaphase↗
PubMed1997

Genetic variability and geographic differentiation among three species of Triatomine bugs (Hemiptera-Reduviidae).

Three species of triatomine bugs, Triatoma sordida, T. guasayana, and T. patagonica, were examined by cytogenetic (C-banded karyotypes and male meiotic process) and isoenzymatic studies. These three species, with different importance as Chagas' disease vectors, were found to be closely related according to their known ethologic, ecologic, and morphologic traits. Although they have the same diploid chromosome number (2n = 22 constituted by 20 autosomes and an XY male/XX female sex mechanism), each species has a distinct chromosomal behavior during male meiosis and a specific amount and localization of C-heterochromatic blocks. Moreover, these chromosome characteristics allowed us to differentiate two T. sordida populations. Isoenzymatic data confirmed the taxonomic status of the three species and together with our cytogenetic results questioned the species homogeneity of T. sordida.

Animals↗
PubMed1997

Competence for nuclear replication and the NOR-chromosomes of Allium cepa L.

Autotetraploid (4n = 32) cells were induced in Allium cepa L. root meristems by successively treating with a multipolarizing agent in anaphase (carbetamide) and an inhibitor of cell plate formation in telophase (caffeine). This treatment produced cells with their 32 chromosomes distributed in more than two nuclei. During G1, one of the nuclei in the resulting trinucleate cells had a DNA content which was equivalent to an average of 16 chromosomes, while the other 16 chromosomes were randomly distributed in two aneuploid nuclei. In the set of 16 chromosomes forming the onion diploid complement, there are 4 NOR-chromosomes and 5 chromosomes carrying DNA domains providing a nucleus with the competence to replicate, as previously shown. Expected probabilities derived from the different possible models for cosegregation of both kinds of chromosomes in the two aneuploid nuclei of the trinucleate cells were estimated by a computer simulation. These expected values were compared with the recorded frequencies of aneuploid nuclei which were able to organize a nucleolus and to respond to inducers of replication. The present data are compatible with the existence of sequences providing a nucleus with the competence to replicate in three out of the four NOR-bearing chromosomes, as well as in two other chromosomes of this diploid complement. The scarcity of chromosomes bearing early origins able to initiate replication in a nucleus is a striking feature of this huge onion genome.

Allium↗
PubMed1996

Nucleolar organizer expression in Allium cepa L. chromosomes.

Roots from Allium cepa L. (cv. Francesa) bulbs in which a maximum of two nucleoli per nucleus developed were selected for this study. Five rDNA clusters were detected by fluorescent in situ hybridization on chromosomal squashes (2n = 16) with a rhodamine-labelled wheat rDNA repeat. The rDNA clusters were located on four chromosomes: the largest cluster occurred on the small arm of a single homologue of the smallest pair 8. Its homologue showed two different small rDNA clusters, one near each telomere. The two homologues of the satellited chromosomes 6 also showed different rDNA contents, which were intermediate to those found in pair 8. The same five well-differentiated hybridization signals were observed in interphase cells that were inactive in transcription because they were in dormant roots, or in proliferating ones in which the synthesis of the large rRNA precursor was prevented. After multipolarizing agent was applied in anaphase followed by inhibition of cytokinesis, multinucleate autotetraploid cells were formed, which often contained more than four nucleoli. Thus, at least two of the three nucleolar organizer regions that consistently failed to develop a nucleolus in normal mononucleate cells were capable of developing nucleoli when segregated into different nuclei in multinucleate cells.

Chromosome Mapping↗
PubMed1995

Karyotype evolution in holocentric chromosomes of three related species of triatomines (Hemiptera-Reduviidae).

C-banded karyotypes, DNA content and the male meiiotic process of Triatoma platensis and Triatoma delpontei are compared with those of Triatoma infestans, the main vector of Chagas disease in South America. These three species present the same diploid chromosome number 2n = 22 (20 autosomes + XX male/XY female). They also have several cytogenetic traits that differ from all other triatomines: large autosomes, C-heterochromatic blocks and meiotic heteropycnotic chromocenters formed by autosomes and sex chromosomes. In spite of these similarities, each species presents different chromosomal behavior during male meiosis, distinct DNA content and a specific amount and localization of the C-heterochromatin. The differences in DNA content are mainly due to the variation in C-heterochromatin amount, which may be interpreted as loss and/or gain of C-regions. This interpretation is supported by the presence of meiotic and mitotic chromocenters that facilitate the transference of C-positive material. The cytogenetic data presented in this work suggest that T. infestans and T. platensis are more closely related to each other than to T. delpontei. It can also be inferred that the differences in distribution and amount of heterochromatin do not play a direct role in speciation in this group.

Animals↗
PubMed1992

A limited number of chromosomes makes a nucleus competent to respond to inducers of replication and mitosis in a plant.

Multinucleate tetraploid cells with unbalanced chromosomal distribution in aneuploid nuclei were obtained in Allium cepa L. root meristems. For this, their natural diploid cells were treated with a multipolarizing agent (1 h carbetamide) followed by an inhibitor of cytokinesis (1 h caffeine). Data from these multinucleate cells with aneuploid nuclei suggest that only four out of the thirty-two chromosomes of their autotetraploid complement possess DNA sequences making the nucleus competent to respond to inducers of replication and mitosis. Direct observation of cells where a single replicated chromosome had reached mitosis showed that this chromosome was the one bearing the nucleolar organizer. Six specific chromosomes would confer competence to the nucleus to respond to inducers of replication but not to those producing chromosome condensation. Another four different chromosomes would confer the nucleus with the ability to respond to mitotic inducers but not to replication inducers. The rest of the chromosomal complement seemed to lack any of the DNA sequences needed for these two important cycle transitions. In a nutshell, certain DNA sequences distributed in a few chromosomes of the onion complement are an intranuclear requirement to initiate replication and mitosis in these plant cells.

Allium↗
PubMed1979

[Sequential scintiscanning with 99mTc-HIDA in the study of some aspects of post-operative dynamics of the proximal digestive tract].

The authors exploited the elective biliary excretion of 99mTc-HIDA at adequate concentrations to afford visibility of intestinal segments more directly wetted by bile in a study of sequential hepatobiliary scintigraphy designed to explore the parts of the duodenum and jejunum that are excluded to the transit of gastrointestinal contents in many surgical procedures involving the proximal digestive tract. They illustrate their case material with several representative examples; these are described in detail to show the validity, usefulness and versatility of the scintigraphic technic under discussion.

Adult↗
PubMedDate not supplied

Cytogenetics as a tool for triatomine species distinction (Hemiptera-Reduviidae).

Several cytogenetic traits were tested as species diagnostic characters on five triatomine species: Rhodnius pictipes, R. nasutus, R. robustus, Triatoma matogrossensis and T. pseudomaculata. Four of them are described for the first time. The detailed analysis of the meiotic process and the application of C-banding allowed us to identify seven cytogenetic characters which result useful to characterize and differentiate triatomine species.

Animals↗